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<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
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<body>
  <script>
    // 1. 声明数组 有序
    let arr = [1,2,3,4,5,6,7,8,9,0]
    console.log(arr)
    // 2. 使用数组 数组名[索引号] 从0开始
    console.log(arr[0])
    // 3. 数组长度
    console.log(arr.length)
    
    
  </script>
</body>
</html>